Thursday, 8 January 2015

What is DCL? / List of operations that can be performed by Data
Control Language / DCL examples / Different DCL commands

Data Control Language (DCL)

Data Control Language is used for
controlling access privileges that are assigned for database users. It is one
of the components of SQL like the DDL and DML. It does the following;

Granting privileges – through DCL we can
permit individual users with individual permissions to access database and data differently.
For example, we can restrict a user only to insert data into a table and to view
data of the table. Some users may be permitted to create tables, some may be
allowed to delete tables and so on.

This can be done with the GRANT command.
For example, the following statement will allow a user to only insert the data
into a table.

GRANT INSERT ON Teacher TO Kumar;

Here, Teacher is the table name and ‘Kumar’
is the name of the user. This statement permits the user Kumar to insert data
into the table Teacher.

Other examples:

GRANT INSERT, SELECT ON Teacher TO Kumar;

GRANT INSERT ON Teacher TO Kumar, User2;

Revoking privileges – we can revoke the privileges
given to an user using revoking privileges statement.

For example, the following query will
revoke the permission given to the user kumar in the previous statement.